okay i know this is definately not recommended by anyone probably anywhere, but due to time circumstance and having to have a vehicle soon i was wondering if there was any way to zero deck a block realitively close without mock up. is there anyway to measure off the bearings or something along those lines? what about taking the stock deck height as .025? i realize nobody is going to like this idea but i figure if i could get it within 1-2 thousandths it would be close enough? the machine shop is only doing the boring and decking and its a long ways away so itd be a real time issue trying to get it there and back twice. also ive heard from a guy who builds 7 second 3rd gen cars that he decks it before he bores it. how is this possible with oversized pistons and doing a mock up before decking? any help is appreciated, thanks.

 

Got to mock it up.
Ya bore it just enough to get a 4.026 piston in the corners,ya measure it,deck it and come back for the final honeing-.004-5.

 

so theres no way to know how far my kb hyper pistons on a 5.7 sir eagle rod with a 3.75 in stroke eagle cast crank will sit in the cylinder in an unmolested LT1 2 bolt block out of a 95 transam?

 

Ya don't know if it is square to begin with. (probably not)I have seen more than one be .018 on LF-.025 on RF,.026 on RR,and .010 on LR so there is no way to know without mocking it up and with the crank rods and pistons that ya gonna run.
Yea ya can do the math but it can't tell ya how it is before ya start.

 

okay so how could i check how square the block is before mock up. if say it was really close within a few thousands then if i figured the stock deck height is .025 would my aftermarket setup be about the same length? if that was true then if the block was true and square i could have it zero decked. its not really the point that im trying to avoid mockup i have to do that for clearancing the rods and cylinders anyways, its just that while its at the machine shop, long damn ways away i want to get all his part done. plus if i have to bring it back twice then he has to work it into his schedule twice. sorry if it looks like im being bull headed im really not trying to be but just want to check out all my options before my car sits for a month if i can get around it.

 

I have the tooling to do a bare block,but don't know if your shop does or not. They should. Ask them,but be prepared for the sticker shock.(got to pay for the tool) Ya may get it within +/-.005. If it's the wrong way (piston out)ya are in deep s*** if ya gonna spray. Ya need to tell them ya want it square decked and equal decked so both sides are the same.

 

Do you have a large selection of calipers and inside gauges?
Measure main saddle bore diameter.
Measure rod big end diameter.
Measure small end diameter.
Measure wrist pin hole.

Halve all of these measurements and write them down.

Measure from upper main saddle bore to deck with huge calipers.
Add half of the main saddle diameter to this. This is your deck height.

Measure from upper rod big end to lower small end bores.
Add half of big end and small end diameters. This is your rod length.

Measure from upper part of wrist pin bore to deck of piston.
Add half of the wrist pin bore diameter. This is your compression height.

You are on your own measuring stroke. I can think of no easy way to do so on the bench.

Add half of the stroke to rod length and compression height.

Subtract this measurement from deck height. This is your deck clearance on paper.

After doing all this you may find it would have been easier to assemble a rod and piston without rings and install it with the crank (just drop in the #1 and 5 main bearings) in the 4 corner holes to get your real deck clearance.

The compression height on aftermarket pistons is often shorter than OEM.

 

They make a tool to do it. It works similar to a dial bore gage.How do ya measure the calipers? Inside mikes ABOUT 10" LONG and ya might get within .025.
Calipers for precise measurements went out with high button shoes and knee socks.

 

alright so, i guess i might just let the engine shop assemble the engine for deck height. im sure itll probably cost quite a bit more and thatll hurt the budget, but i suppose its gotta be done, better than not doing it right and having something horrible happen like the piston run into the head or something. so with my fel pro .039 gasket, i assume zero decking the block is what i should do. thatd put my quench just right.

 

Yep-- for a street engine on 92 octane.

 

Really the "Pro" way of doing it is actually have the parts verified to be the correct dimension. Rod length, compression height, and stroke length can and very often do vary, this is why you're going through all of this in the first place. Using the factory short block to check block squareness isn't a great idea, though a major problem would probably show up.

Not bagging on anyone, but blueprinting really should be handled with all the parts at the machine shop doing the work. Otherwise you can't be sure of what's really needed. My previous suggestion sucks only a little bit less than doing nothing at all.

Be careful when squaring your block if you decide to do so. Many boring bars locate off the deck and sometimes a shop will use a BHJ bore-tru plate to locate your cylinders after squaring. A problem that may arise is that with a .030" overbore the boring bar may end up mouse eyeing at the bottom of the bore if the block was way off to begin with. This means part of the cylinder wouldn't be machined. Not to sound alarmist or anything as it isn't very common but it can happen.

 

yeah i talked to my machinst today and i think with my pistons and rod length he can do it with measuring off the main bore. this guy who builds race engines i believe does it this way, from what i can tell. he said hed build my engine, but i definately dont have the money for that guy, haha, although he is a local here and i know him pretty wel, so ill probably try and borrow some more of his knowledge.